Hey Rob...
This is an invite i did for my 7 yrd old's birthday party, i used the app Half-Tone to create the six panels you can see.
Although i'm not sure if this qualifies to be your artwork as it isn't 100% exclusively done on iOS, perhaps 90 something percent as i did use Adobe Fireworks to join them together as one image.
But i thought you and the listeners might like to see it.
Thanks
Doug